Mass Spectroscopy Flashcards
What are 3 uses of mass spectrometry?
1) Relative atomic mass
2) Relative isotopic abundance
3) Relative molecular mass
What are the 4 main stages of mass spectroscopy?
1) Ionisation
2) Acceleration
3) Flight
4) Detection
What are the 2 main methods of ionisation?
Electron impact
Electro-spray ionisation
What is electron impact?
A high energy electron gun knocks off an electron, forming positive ion
What is electro-spray ionisation?
1) Dissolve sample in volatile solvent
2) Inject through hypodermic needle - fine mist
3) Attach tip of needle to high voltage supply
4) Particles are ionized by gaining a proton (from solvent)
What is acceleration?
Using an electric field so all ions gain the same kinetic energy.
Lighter ions travel faster than heavier ions
What is the ion drift?
Ions enter region with no electric field, so they drift through it. Lighter ions drift through faster than heavier ions
What is detection?
Positive ion hit negatively charged plate where it will collect an electron - creates current & mass spectrum is produced
M+
Molecular ion
